By Carrie Madormo, RN, MPH 

 Medically reviewed by Kiarra King, MD

Pregnancy-associated osteoporosis is a rare condition that causes low bone density and fractures during and after pregnancy.1

It most often affects the bones in the spine and hips.2 The most common symptoms of pregnancy-associated osteoporosis are severe pain and disability.3 

This article discusses the causes, diagnosis, and treatment of pregnancy-associated osteoporosis.

Sarah McEwan / Getty Images

The exact number of people affected by pregnancy-associated osteoporosis is unknown.4 Osteoporosis impacts 10 million adults over the age of 50 in the United States. Pregnancy-associated osteoporosis is estimated to affect fewer than 200,000 pregnant people each year.5

How Pregnancy Affects the Bones

It is common for pregnant people to lose bone density during pregnancy. The growing fetus needs calcium to form a skeleton. If a pregnant person does not get enough calcium from their diet, the body will draw calcium from the bones to help the baby grow. 

People who are breastfeeding also lose calcium from their bones. It’s estimated that breastfeeding people lose 3–5% of their bone mass and recover it after weaning.6 

Most pregnant people do not experience any bone problems and recover their bone density when breastfeeding has stopped. To protect your bones during pregnancy and breastfeeding, take the following steps:6

• Consume 1,000 milligrams of calcium from food or supplements per day

• Exercise daily, especially weight-bearing and resistance activities 

• Ask your healthcare provider for resources to help you quit smoking 

What Is Pregnancy-Associated Osteoporosis?

People with pregnancy-associated osteoporosis usually experience bone fractures during birth or eight to 12 weeks following delivery. The cause is typically unknown and does not appear to be linked to a person’s age, hormone levels, or calcium intake. The most common symptom of pregnancy-associated osteoporosis is severe back pain.7

Pregnancy-associated osteoporosis is very rare. Estimates suggest that the prevalence of osteoporosis is less than 2% in women younger than 50 and only 1.2% in women between the ages of 20 and 40.7

Causes and Risk Factors

The exact cause of pregnancy-associated osteoporosis is unknown. Pregnant people have a higher level of estrogen, which is usually good for bone strength. Most people who menstruate do not experience bone loss until their estrogen levels fall with menopause.8

Possible risk factors for bone density issues during and after pregnancy include:7

• Family history of osteoporosis

• History of disordered eating

• Crohn’s disease

• Inflammatory bowel disease (IBD)

• Osteogenesis imperfecta and other bone diseases 

• Heparin (blood thinner) use

• Thyrotoxicosis (excess thyroid hormones)

Diagnosis

Pregnant women are usually evaluated for pregnancy-associated osteoporosis when they report severe back pain. Performing an X-ray or other imaging study can reveal fractures in the bones that make up the spine (vertebral compression fractures). These fractures usually develop during the third trimester or after delivery.9 

Imaging studies for diagnosing pregnancy-associated osteoporosis include:9

• Magnetic resonance imaging (MRI)

• Computed tomography (CT) scan

• 3D CT scan 

• Dual-energy X-ray absorptiometry (DEXA) scan

• Bone biopsy

People with pregnancy-associated osteoporosis are more likely to experience:9

• Premature contractions

• Vaginal bleeding

• High blood pressure (hypertension)

Treatment and Recovery

You should treat pregnancy-associated osteoporosis with the guidance of your healthcare team. The goal of treatment is to prevent new fractures, relieve back pain, and increase bone density. 

Conservative treatment for pregnancy-associated osteoporosis includes:9

• Weaning breastfeeding

• Diet rich in calcium (dark leafy greens, chia seeds, dairy)

• Calcium supplement

• Vitamin D supplement

• Staying active (avoiding bed rest)

• Avoiding heavy lifting 

Medications that may treat pregnancy-associated osteoporosis include:7

• Bisphosphonates: Prevents bone loss but may affect the fetal skeleton 

• Teriparatide: Increases bone density and decreases the risk of fractures without affecting the fetus 

• Calcitonin: A hormone that lowers blood levels of calcium 

• Prolia (denosumab): Human monoclonal antibody

• Strontium ranelate: Helps to grow new bone tissue

Impact of Pregnancy-Associated Osteoporosis on the Baby

Fortunately, people with pregnancy-associated osteoporosis can have healthy pregnancies and babies. Though this rare condition does not affect the development or health of the fetus, the treatment options might. 

Certain medications that treat pregnancy-associated osteoporosis, such as bisphosphonates, may affect the fetus and future pregnancies. When determining a treatment plan, it is important to tell your healthcare provider if you plan to have more children. Pregnancy-associated osteoporosis is more common during a person’s first pregnancy but may also occur in subsequent ones.7 

People with pregnancy-associated osteoporosis can breastfeed safely as long as they are not taking any medications that they can pass to the baby through breast milk. 

Does Pregnancy Cause Osteoporosis Later in Life? 

It is normal for pregnant and breastfeeding people to lose bone density. Fortunately, most people recover their bone density over time. Estimates suggest that a person’s bone density returns to normal levels by the time their child is 1 year old. People who breastfed are expected to reach a normal bone density six months after weaning.5 

Teenagers who become pregnant are at an increased risk of low bone density during and after pregnancy because their skeletons are still developing. They are also at an increased risk of developing osteoporosis later in life.6 

Summary

Pregnancy-associated osteoporosis is a rare condition that causes low bone density and fractures in people during and after pregnancy. Bone loss most commonly occurs in the back and hips. Severe back pain is a possible sign of pregnancy-associated osteoporosis. The exact cause of this condition is not always known. It can be diagnosed with a physical, a health history, and an imaging study. Pregnancy-associated osteoporosis can be treated with a calcium-rich diet, supplements, and medications. 

Sources

Hardcastle SA. Pregnancy and lactation associated osteoporosis. Calcif Tissue Int. 2022;110(5):531-545. doi:10.1007/s00223-021-00815-6

 Jia P, Wang R, Yuan J, et al. A case of pregnancy and lactation-associated osteoporosis and a review of the literature. Arch Osteoporos. 2020;15(1):94. doi:10.1007/s11657-020-00768-7

Hardcastle SA, Yahya F, Bhalla AK. Pregnancy-associated osteoporosis: a UK case series and literature review. Osteoporos Int. 2019;30(5):939-948. doi:10.1007/s00198-019-04842-w

Royal Osteoporosis Society. Pregnancy-associated osteoporosis.

Columbia University Irving Medical Center. Rare form of osteoporosis around pregnancy gets spotlight at Columbia.  

National Institute of Arthritis and Musculoskeletal and Skin Diseases. Pregnancy, breastfeeding and bone health.

Yun KY, Han SE, Kim SC, et al. Pregnancy-related osteoporosis and spinal fractures. Obstet Gynecol Sci. 2017;60(1):133-137. doi:10.5468/ogs.2017.60.1.133

Hospital for Special Surgery. Pregnancy and bone density: what to know.

Cerit ET, Cerit M. A case of pregnancy and lactation associated osteoporosis in the third pregnancy; robust response to teriparatide despite delayed administration. Bone Rep. 2020;13:100706. doi:10.1016/j.bonr.2020.100706

By Carrie Madormo, RN, MPH
Madormo is a health writer with over a decade of experience as a registered nurse. She has worked in pediatrics, oncology, chronic pain, and public health.